Compressor



Dec. 12, 1933. A. J. KERCHER 1,939,057

COIPRES S OR Filed Feb. 24, 1930 4 Sheets-Sheet l INVENTOR. fi/WA/i J/fitecwzw A TTORNE Dec. 12, 1933. A. J. KERCHER 1,939,057

COMPRESSOR Filed Feb. 24, 1930 4 heets-sheet s A TTORNEYS.

Dec. 12, 1933. A. J. KERCHER 1,939,057

COMPRESSOR Filed Feb. 24, 1930 heets-Sheet 4 ATTORNEYS.

Patented Dec. 12, 1933 COMPRESSOR Arthur J. 'Kercher, Berkeley, Calif.

Application February 24, 1930. Serial No. 430,563

2 Claims.

This invention relates generally to compressors such as are employed for performing work upon gaseous mediums, and which are of particular value when applied in refrigeration systems for compressing a fluid refrigerant.

It is an object ofthe invention to generallyimprove upon compressors of the type disclosed in my copending application No. 334,571, filed January 23, 1929, now Patent No. 1,882,220, of October l-1,"l932, for Refrigerator system and apparatus.

' It is a further object of the invention to devise a compressor of relatively light and simple construction, which will occupy a minimum amount of space for its capacity;

It is another object of the invention to devise a compressor which will operate smoothly with a minimum amount of noise and vibration.

Further objects of the invention will appear from the following description in which the pre,-:

ferred embodiment of the invention has been setforth in conjunction with the accompanying drawings. It is to be understood that the appended claims are to beaccorded a range of equivalents consistent with the state of the prior art." Referring to the drawings: 7 Figure 1 is a side elevational view in cross section illustrating a refrigerating system embodying the compressor of thepresent invention.

Fig. 2 is an enlarged cross'sectional detail taken along the line 22 of Fig. 1.

Fig. 3 is a crosssectional detail of a portion of the piston and cylinder assembly, showing parts in a diiferent operatingv position'from that illustratedin Fig. 2.

Fig. 4 isan enlarged cross sectional detail taken along the line 4 4 of Fig. l. I I

Fig.5 is a detail illustrating the stationary valve member utilized in my compressor, in plan.

Fig. 6 is a side view of the valve member shown in Fig. '5.

Fig. '7 is a view similar to Fig.- 6, but with the" valve member rotated thru 180 degrees.

Fig. 8 is a cross sectional view of the valve membertaken on the line 8 8 of Fig. 7.

Fig. 9 is a quarter sectional detail illustrating the relationship between the piston cylinder assembly and the actuator".

views illustrating the manner inwhich thevalve member and its ports cooperate with ports in the cylinder structure. 7 a

The compressor as disclosed in my copending application No. 334,571 comprises a cylinder struc- Figs. 10, 11 and 12 are diagrammatic detail ture adapted to rotate about a relatively stationary shaft. The pistons, or piston assemblies, disposed within the cylinders of this structure, are adapted to be reciprocated by an actuator, the actuator being mounted so as to rotate about an axis parallel to but eccentric to the axis of rotation of the cylinder structure. The stationary shaft is provided'with a valve or distributor member which cooperates with ports in the cylinder structure to control introduction and discharge of the gas being compressed. The actuator disclosed in that application is in the form of a'ring, and the pistons are held in operative engagement with the inner cylindrical surface of this ring by centrifugal force.

In devising a compressor of this general type having reduced overall dimensions and weight; I have found that the use of a ring type actuator imposes certain limitations. For example when the diameter of the ring is reduced, the effect of the inner arcuate surface which is in engagementiwith the pistons tends to 'detrimcntally affect the compression cycle and to modify movements of the pistons so as to seriously reduce the compressor capacity. Furthermore a ring type of actuator is undesirable from the standpoint of weight and cost of manufacture. In the present invention a web type actuator has been utilized in place of a ring, and by the use of novelmeans this actuator is caused to rotate with the same angular velocity as the cylinder structure.

rthermore the surfaces of the actuator which are engaged by the pistons, are formed in such a manner that the pistons are properly recipro' cated to secure adequate capacity and efficiency.

While the present invention is chiefly con cerned with the compressor construction, in Fig. l I have shown a refrigerator apparatus incorporating the compressor of the present invention. This apparatus comprises a sealed metal casing 10, provided with an upper readily removable casing section 11 Circumferentially spaced cooling fins l2, and 13 are mounted upon the upper and lower casing sections, and the upper casing section 11 is held in sealed position by means of the detachable tie rods 14. Pipe 16 extends thru the lower portion of the casing and serves as a discharge" for compressedfiuid' refrigerant, while pipe 17 serves as a refrigerant intake. Pipe 16 connects with the condenser 18, which in turn is connected the expansion valve 22. The vaporized refrigerant from absorber 21 is returned to the cycle thru pipe 23. Positioned within the casing 10 there is a motor compressor unit 24, which consists of a suitable motive means such as an electric motor 26, mechanically connected to drive the compressor 27. The motor compressor unit 24 in its normal operation develops considerable heat, which is transmitted to the walls of casing 10 and to fins 12 and 13, and is thus dissipated to convection currents of air. In order to augment flow of convection currents of air thru the cooling fins and to enhance appearance of the apparatus, the fins and condenser 18 can be surrounded by a suitable housing 28.

The motor compressor unit 24 can consist of a frame 29 serving as a mounting for both the electric motor 26 and the compressor 27. A suitable form for this frame consists of a ring shaped member 31, within which the motor stator 32 has a forced fit. Another ring shaped member 33 serves to encompass the moving parts of the compressor 27, and is rigidly connected to ring member 31 by the upper connected member 34 and sideconnecting members 36. (Fig. 4 Mounted within the frame 29 there is a relatively stationary shaft 3'7, about which both the motor and compressor are disposed. One end of shaft 37 is inserted within a socket member 38, which in turn is carried by end portion 39 of frame 28,- while the other end of the shaft is extended thru an end spider plate 41, this plate being removably secured to the main frame by means of bolts 42. The end of the shaft extending thru plate 41 is preferably threaded and engaged by a suitable clamping nut 43.

' The compressor 2'7 preferably consists of a cylerably extend radially with respect to the shaft 37 and to the axis of rotation. Any convenient number of cylinder bores can be provided depending upon the required capacity of the compressor and upon the conditions under which the compressor is to operate. For convenience I have shown only four cylinder bores, as this'nurnber has been found sufficient when the compressor is employed in a domestic refrigerator. Fixed upon the shaft 37 within the cylinder structure 44, there is a valve or distributor member 4'7. While this member can be'made integral with shaft 3'7, it is preferably formed as a separate member which can be positioned about the shaft and retained in fixed relationship with respect "to the same, by means of a suitable centering pin or key. Valve member 47 has a peripheral surface which is preferably cylindrical in contour, and

which closely fits a complementary bore in the.

cylinder structure 44, thus providing a cylindrical sealing surface 48 as shown in Fig. 2. To avoid forming a bearing directly on valve member 47, one end of cylinder structure 44 is suitably journaledon shaft 37 as by means of a ball bearing assembly 49, while the other end can be sup ported by the drive connection to motor 26, as will be presently explained. Disposed within each of there is apiston or piston assembly 51, and these pistons are reciprocated in a manner to be presently explained. While separate ports may be employed for introduction and discharge of fluid into each cylinder bore, I preferably employ a single port 52, which communicates with the innor end of each cylinder bore and the sealing the cylinder bores 46,

- casing 10.

surface 48. In order to prevent any actual pumping of fluid until the compressor has attained a predetermined speed, thus permitting starting under substantially no load, I preferably provide means in conjunction with pistons 51 for effecting automatic control according to the speed of rotation of the cylinder structure. This means preferably takes the form of valve members 53 which are carried by pistons 51. Each valve member 53 is provided with a fluted stem 54 which normally extends thru a sleeve 56. Sleeve 56 is fixed to the bottom wall of the correspond ing piston 51, and is substantially in alinement with the port 52 of the corresponding cylinder bore. Positioned within each sleeve 56 there is a compression spring 57, which normally tends to urge the associated valve member 53 and piston 51 apart, and to cause this valve member to normally seat within its corresponding port 52 as has been shown in Fig. 3. Spring 57 is of such strength that it serves to keep the valve member 53 within the port 52 until the speed of rotation of the cylinder structure has attained a predetermined value, after which the centrifugal force exerted by virtue of the mass of valve member 53 and its associated stem serves to overcome the tension of spring 57 and thus move valve member 53 outwardly to seat upon the bottom surface of piston 51, as shown in Fig. 2. It will'be noted that when valve member 53 is in the position shown in Fig. 3, the interior of sleeve 56 forms a by-pass between opposite sides of the associated piston 51, while in the position shown in Fig. 2, this by-pass is closed. Thus when the compressor is started into operation and the cylinder structure is rotating at a relatively slow speed, inflow and discharge of fluid thru ports 52 is interrupted by valve members 53, and pistons 5l'are free to reciprocate by virtue of the fact that fluid is by-passed into and out of the cylinder bores thru the interior of sleeve 56. How- 7 ever after the compressor has attained normal speed and the valve members have been moved by centrifugal force to the position shown in Fig. 2, fluid is free to enter and to be discharged from the cylinder bores and cannot bypass thru sleeve 56.

For effecting reciprocation of the pistons I preferably utilize an actuator 61, which is preferably in the form of a Web as shown in Fig. 4. In order to mount this actuator in such a-manner that it can rotate together with the cylinder structure 44, I have shown it provided with a suitable hub 62, carried by ball bearing assembly 63. The axis of rotation of actuator 61 is parallel to but eccentric to the axis of rotation of the cylinder structure 44. To form portions for cooperating with the pistons, actuator 61 is provided with radially extending arms 64, having portions66 which overlie the outer ends of cylinder bores 46. These portions 66 have inner surfaces 6'7, which are preferably relatively flat and substantially parallel to the axis of rotation of both the cylinder structure and the actuator. As shown in Fig. 2, surfaces 67 are also preferably substantially perpendicular or normal to radii drawn from the center of rotation of the actuator to the centers of surfaces 67. It is evident that this actuator 61 is relatively light in construction, and thatit permits the pistons and other moving parts of the compressor to be subjected to a spray of lubricating oil which is generally normally maintained within the enclosing Interposed between each piston 51 and its associated actuator portion 66, I provide a thrust ball 68 or equivalent means. Each ball 68' can be loosely retained by a suitable socket 69, which in turn is mounted upon the outer end of the associated sleeve 56. e

A mechanical connection is formed between the actuator and the cylinder; structure 44, in order to cause theseparts to rotate in synchronism. This mechanical connection is preferably such that the angular velocity of the cylinder structure and theactuator is always the same, that is, so that when the cylinder structure is being rotated at a constant speed, the actuator will also rotate at the same speed without deceleration or acceleration. A simple and highly practical mechanical connection can be formed byproviding a plurality of pins 71 mounted upon the, inner face of actuator 61. A plate or disc 72 is fixed to one side of cylinder structure 44 adjacent actuator 61, and this plate is provided with a plurality of apertures 73 into which pins 71 extend. The projecting ends of pins 71 are preferably cylindrical and apertures 73, are preferably circular so as to provide cylindrical surfaces 74 for contacting with the sides of pins 71. A suitable distribution for apertures 73 and pins 71 is shown in Fig. 4. The radius of each aperture 73 is preferably equal tothe eccentricity between the actuator and the cylinder structure, plus one-half the diameter of pin 71. It is therefore evident that for any position of the actuator, pins 71 will engage arcuate surfaces 73 so as to always form a positive drive connection be,

tween the actuator and the-cylinder structure. Furthermore assuming a constant speed of rota tion of the cylinder structure 44, the actuator will likewise rotate at a constant speed, at the that cylindrical surfaces 73 need not be completely cylindrical, since the provision of semicylindrical arcuate surfaces will function together with pins 71 so as to always form a positive drive connection. Thus in place of apertures 73, I can member 47 can best be understood by reference to Figs. 5 to 8 inclusive. Along one segmental portion of the periphery of this valve member, there is provided a recess or port 76 for inflow of fluid into the cylinders. In addition to the recess 76 and communicating therewith, there is a groove 77, this groove being alined with respect to and of substantially the same widthas the ports 52. Groove 77 is substantially deeper than the recess 76 as shown in Fig. 8 to permit flow of fluid into ports 52, with a minimum of resistance,

Vanes 78 are located upon opposite sides of groove 77 and serve to isolate a portion of this groove from recess 76. As shown in Fig. l recess 76 communicates with an annular pocket 79 in the cylinder structure 44, and this pocket in turn communicates with the interior of casing 10 thru a plurality of radially extending ports 81. The radial positioning of ports 81 is a distinctadvantage in that it serves as centrifugal means for effecting separation of oil from refrigerant fluiddrawn.

relatively high value.

intothe compressor. Certain lubricating features of mycompressor will be presently explained, but it may be noted at this'point that oil ducts 82 are formed within valvemember 47, and communicate with recess 7.6. at points located between vanes 78 and the-ends of valve member v47, as shown in Figs. 5 and 6. Ducts 82 communicate with a common duct 83, to which oil is supplied as will be presently explained.

For controlling the discharge of compressed fluid, there is provided a port 84 which communi cates with the periphery of valve member 47 at a' point spaced from the recess 76. Port 84 is substantially the same diameter as and is alined with the ports 52 of the cylinder structure. In addition to the port 84, the periphery of valve member 47 is interrrupted by a circumferentially extending groove 86, one end of which communicates with port 84 as shown in Fig. 8. This groove is of restrictedarea compared to the cross sectional area of port 84. Furthermore it is in the form of a labyrinth so that flow of expansible fluid along groove 86 towards port 84 can occur.

with less attenuation and resistance than flow backwardly from port 84 along groove 86. As will be presently explained this characteristic is for the purpose of preventing re-expansion under certain operating conditions. A labyrinth groove of this character can be conveniently provided by forming a plurality of pockets 87 faced toward the discharge port 84.

The manner in which ports 52, 84, and groove 86 cooperate can be best understood by reference to Figs. 10, 11 and 12. Fig. 10 represents the relative position of a port 52 when the associated piston is just commencing its down or. compression stroke. Fig. 11 shows the position of port 52 during an intermediate part of the compression stroke in which itwill be noted that port 52 is in communication with groove 86. Assuming that the pressure within port 84 is at this time substantially less than the pressure within the associated cylinder, a certain amount of the fluid from the cylinder will be bled thru the groove 86. At the end of the compression stroke, the ports 52 and 84 are in registry as shown in Fig. '12. Under certain operating conditions, as are encountered when'a compressoris employed in a refrigerating system, the pressure in the fluid system supplied by the compresscrmay reach a Under such conditions when a port 52is initially in registry with groove 86, as for example as shown in Fig. 11 the pressure in port 84 may exceed the pressure within the associated cylinder. Thus there will be a tendencyjfor: fluid to re-expand and flow back thru groove 86. Such re-expansion causes a loss .in (-JfilCle Qy and is minimized by my invention because of the labyrinth character of groove 86.

For the opposite extreme "operating condition, as

for example when'the pressure in port 84 is at atmospheric or below, the extent of groove 86 automatically causes a lowering of the meaneffective pressure within the associated cylinder.

.Thus my compressor not only gives good efliciencywhen' operating under normal optimum conditions but is also comparatively efiicient for extreme operating conditions. This characteristic is of particular value when. the compressor is employed in refri erator systems, where the pressure in the condenser to which the compressor discharges varies over wide limits.

, Referringnow to Figs. 1 and 2, discharge port '84 communicates with the discharge passage 88 inv shaft 37, when valve member 47 is in normal position. Passage 88 in turn communicates with the passagej'89 in theend plate 41 of frame 34, from which fluid is conducted to discharge pipe 16. Intake pipe 17 has its upper end 91 open to the interior of casing 10, thus communicating thru the casing with the intake ports 81 of the compressor.

Since my compressor is of such a character that it performs practically no work upon the fluid being compressed until its speed is increased above a certain value, comparatively small starting torque is required for the motor 26. This motor can therefore be a simple induction type single phase motor connected to a phase splitting or other convenient form of starter. The rotor 94 ofthis motor is shown mounted upon a sleeve 96, this sleeve being journaled upon shaft 37 as by means of a ball bearing assembly 97. One end of sleeve 96 is keyed or otherwise rigidly connected to the projecting portion 98 of the cylinder structure 44.

When the compressor is in operation it is preferably subjected continuously to a spray of lubricating oil. This spray of oil not only affords Ilubrication for exposed lubricating parts, but it also serves to conduct away heat from the compressor motor unit and to transfer this heat to the casing 10. For this purpose I have shown a quantity of lubricating oil 99 in the lower por- "tion of casing 10, the level of this oil being preferably above the lower portion of ring member 33. The inner periphery of ring member 33 is preferably formed to provide an annular concavity 101, into which oil can flow thru slot 102. A lug 103 projecting from the portion 66 of the actuator, serves to dip into the oil and splash the same over the motor and compressor and in addition to cause oil to flow along the inner periphery of member 33 thru cavity 101. The upper portion of ring member 33 is provided with an inclined slot 104, thru which oil can flow into a groove 106 formed upon the upper side of frame 44. Due to the shape of frame 44, groove 106 is inclined toward the motor: end where the oil flows downwardly thru two separate ducts 109 and 111. Duct 109 supplies oil to the motor ball bearing assembly 97.- By means of a duct 112 in shaft 37, duct 111 supplies oil to ducts 83 and 82 of valve member 47. Ball bearing assembly 49 and 63 are lubricated by oil splashed upon the same and by oil escaping from the sealing'surface 48, which is supplied thru duct 82.

To provide adequate lubrication for the pistons I prefer to provide one or more ducts 116 thru the side walls of each cylinder as shown in Fig. 2. As convenient means for supplying oil to these ducts, each cylinder is provided with an inwardly faced pocket 117, preferably formed by means of a ring 118. Oil can be supplied to pocket 117 from excess lubricant applied to the sealing surface 48; For this purpose there is shown an annular groove 119 near that end of valve member 47 which is farthest from the motor, and this groove is in communication with the exterior surface of the cylinder structure 44 thru one or more ducts 121. Likewise at the other end of valve member 47, I have shown an annular groove 122 connected to the exterior surface of the cylinder structure thru one or more ducts 123. Oil which flows thru ducts 121 and 123 moves outwardly by centrifugal force along the side walls of the cylinders and is collected by pockets 117, from which his delivered to the inner cylinder walls thru ducts 116.

In order to minimize transmission of noise and vibration to the casing 10, I preferably provide a resilient or shock absorbing mounting for the motor compressor unit 24. Such a mounting is shown in the drawings and consists of a plate 126 resting on the bottom of the casing 10. A plurality of standard members 127, three in this instance, are secured to and extend upwardly from plate 126, and are provided at their upper ends with sockets 129. Supporting springs 131 are positioned Within sockets 129, and theupper ends of spring 131 carry socket members 132 which are secured to the frame 34 of the motor compressor unit. The entire motor compressor unit is out of direct contact with side walls of the casing 10, except for the connection thru the spring 131.

For making electrical connections to the motor, I have shown a sealed electrical conduit 134 extending upwardly thru the bottom of casing 10 and carrying a terminal block 136. The motor windings are connected to this terminal block thru a flexible electrical cable 137. Electrical cable 138 extends from terminal block 136 down thru the conduit 134, and connects to a suitable external supply line.

As has been previously described, I preferably draw the fluid to be compressed into the compressor directly from the interior of casing 10. The control valve 22 is preferably adjusted so that when the compressor is in normal operation it produces a comparatively low sub-atmospheric temperature within the casing. A rarefied atmosphere of this character will not readily transmit noise from the motor compressor unit to the casing walls and therefore materially assists in producing noiseless operation.

Operation of the complete apparatus can be briefly reviewed as follows :When current is applied to the motor, the cylinder structure 44 of the compressor starts rotating about shaft 37, and the rotation is accelerated until the motor reaches normal speed. Actuator 61 is caused to rotate in exact synchronism with the cylinder structure. Until the compressor has reached a predeterminedspeed, valve members 53 are retained within ports 52, so that there is no pumping action. Therefore very little torque is required to start the compressor into rotation. After a predetermined speed has been attained, which speed is substantially less than thenormal rate of rotation, valve members 53 are moved outwardly by centrifugal force and the compressor begins to circulate and compress the refrigerant fluid. The refrigerant as it is drawn thru ports 81 is subjected to centrifugal action which effects separation of entrained oil from the same. It may be noted that when the speed of the compressor is relatively slow, as when starting the same, this centrifugal separating action is negligible but at this time the compressor does not circulate the refrigerant. By the time the centrifugal force has caused the compressor to start its pumping operation, the centrifugal separating action of passages 81 is effective. Referring to Fig. 2 and assuming that the compressor is rotating in a counter clockwise direction as viewed in this figure, the intake stroke for a particular piston occurs when this piston is moved thru an angle of degrees from, for example, its upper position in this view 1 is moved downwardly on its compression stroke. For about the last degrees of the compression stroke, port 52 is in communication with the discharge of the compressor thru labyrinth groove 86 and port 84. The moving parts of the compressor unit are properly lubricated both by oil which is splashed upon the external parts when the compressor is in operation, and by positive circulation of oil thru ducts previously described.

While the actuator 61 rotates in exact synchronism with the cylinder structure 44, a certain amount of relative rotation occurs between each portion 66 of the actuator and its associated piston 51, due to the eccentricity of the actuator relative to the axis of the cylinder structure. This relative movement between each portion 66 and its associated piston is accommodated by rolling motion of the associated thrust ball 68, thus avoiding any sliding action. connection it will be noted that each socket 69 is sufficiently large to permit adequate rolling movement of its associated ball 68, thereby not only permitting such movement but at the same time properly retaining the ball 68 in operating position. Likewise since surfaces 67 are relatively flat, the thrust thru each ball 68 is always in a direction substantially axially with respect to the associated piston 51, and therefore substantial lateral thrust components tending to cramp the pistons against the sides of the cylinder walls are avoided. Likewise the overall diameter of the compressor can be made'relatively In this smaller than is possible with an actuator having an inner cylindrical surface bearing upon the thrust balls 68, since the flat surfaces 69 permit proper reciprocating movements of the pistons.

I claim: V

1. In a compressor, a rotatable cylinder and piston assembly, an actuator adapted to rotate about an axis eccentric to the axis of rotation of the assembly, a ball freely disposed between each piston of said assembly and the actuator for transmitting thrust from the actuator to the piston associated with said ball, said ball abutting against the concave side of a curved surface on the associated piston, the radius of curvature of said surface being substantially greater than that of the ball.

2. In a compressor, a rotatable cylinder and piston assembly, an actuator adapted to rotate about an axis eccentric to the axis of rotation of the assembly, a ball freely disposed between each piston of said assembly and the actuator for transmitting thrust from the actuator to the piston associated with said ball, said ball abutting against the concave side of a curved surface on the associated piston, the radius of curvature of i ARTHUR J. KERCHER. 

